In certain applications, for example within the car radar field, there is a need for an antenna device having an antenna beam which can sweep a limited range of angle in the order of magnitude of some ten degrees, for example 20.degree., but which does not need to cope with large angle sectors or a complete revolution.
A conventional method for sweeping a region is to rotate both the feeder and the antenna reflector. In this way, both small and large ranges of angle can be swept. Known realizations of this method have proved however to be both costly and space-consuming and are not suitable for use in a car radar, for example, in which the space which might be available for use is very limited and the need for a low price is extremely important.
It is also known to realize the sweeping electronically using a fixed antenna. In order to realize a sweeping of the region according to the above, as is required in a car radar, the solutions remain complicated and expensive and limitation to a smaller sweeping range in which simpler solutions can be utilized has an adverse effect upon the functioning and reliability of the car radar.
In order to realize sweeping within a limited region, it has previously been proposed to utilize a rotatable reflector in combination with a fixed feeder. The reflector can in this case be driven, for example, by means of a stepping motor.